Six degrees of separation refers to the idea that, if a person is one "step" away from each person he or she knows and two "steps" away from each person who is known by one of the people he or she knows, then everyone is no more than six "steps" away from each person on Earth.Social networking site Orkut lists the steps if they are less than 2, but that's as far as it goes. With hundreds of people in the "friends" list, there are millions of links between people. This makes the problem very expensive computationally to solve, and it's no wonder Orkut gives up at 2.
A related concept for movie roles is the Kevin Bacon number i.e. if actor X acted in some movie with actor Y who acted in a movie with Kevin Bacon, the Kevin Bacon number of X is 2. For e.g. Al Pacino has a Bacon number of 2 since:
Al Pacino was in Godfather: Part III, The (1990) with Eli Wallach
Eli Wallach was in Mystic River (2003) with Kevin Bacon
I stumbled upon a cool site by some folks at the The University of Virginia CS department called the The Oracle of Bacon at Virginia, which lets you calculate the Bacon number of any actor you can think of. The Advanced Search option lets you find the separation between any 2 actors not just Bacon. And since they get their data from IMDB, the site works with Indian and other international actors too :). Really cool. Check it out.